Butternut

After the color of the Confederate uniform.

Butternut (plural Butternuts)

1. (US, 19th century) Southern settlers of the Ohio river basin, who used dye from the butternut tree to colour their home-made clothing
   • 2011, Colin Woodard, chapter 17, in American nations, New York: Penguin, →ISBN:

     Yankees took to calling the Borderlanders “butternuts”—a reference to the color of their crude homespun clothes.

2. (US, obsolete) A Confederate Southerner, or somebody who supported southern rights and slavery [19th c.]
   • 1958, Shelby Foote, The Civil War: A Narrative. Vol. 1: Fort Sumter to Perryville.:

     The Illinois troops delivered a volley that sent the butternuts scampering back across the field.

• nut butter